The present invention relates to a liquid filter, in particular an oil filter of an internal combustion engine, having a filter housing having a removable screw cover and having a raw liquid inlet and a clean liquid outlet, having a filter insert that is situated exchangeably in the filter housing and that separates a raw side and a clean side of the liquid filter from one another, the filter housing further having a central discharge duct for emptying the filter housing when the filter insert is removed, a closing pin that is fixed to the housing in the installed state and that has at least one radially sealing seal in a sealing seat in the discharge duct being capable of being axially displaced between a lower, closed position, assumed when the filter insert is installed and the screw cover is closed, and an upper, open position, assumed when the screw cover is removed and the filter insert is removed, and mechanical, releasable coupling elements being provided between the screw cover or filter insert on the one hand and the closing pin on the other hand. Moreover, the present invention relates to a filter insert for a liquid filter.
EP 1 307 274 B1 indicates a liquid filter for cleaning liquids such as lubricant oil, water, or fuel. The liquid filter has a filter housing, a filter element, a supporting body, and a slide valve. In the closed state, the slide valve prevents liquid from being able to flow from the raw side or from the clean side into a liquid discharge duct. As soon as the filter housing is open, the slide valve is moved axially, releasing the liquid discharge duct and making it possible for the filter housing to empty. In this liquid filter, the slide valve is releasably snap-connected to a supporting body that is connected to a housing cover. In this way, the slide valve can be separated from the supporting body. This is advantageous because the separation of the components from one another reduces the level of maintenance required for the liquid filter.
However, in the known liquid filter it has turned out to be disadvantageous that the connecting means by which the slide valve is snap-connected to the supporting body tends to become damaged, in particular to break, during operation. In this way, parts of the connecting means can move to the clean liquid side of the filter, and from there to downstream components, such as, in the case of an oil filter, an internal combustion engine having points that have to be supplied with lubricant, where damage can occur as a consequence. Moreover, during a filter maintenance the connecting means must be separated from one another manually, in particular by exerting adequate tensile force.